// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
//  This source code is licensed under both the GPLv2 (found in the
//  COPYING file in the root directory) and Apache 2.0 License
//  (found in the LICENSE.Apache file in the root directory).

package org.rocksdb;

import com.zto.fire.common.util.PropUtils;
import org.rocksdb.util.Environment;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.*;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;

/**
 * A RocksDB is a persistent ordered map from keys to values.  It is safe for
 * concurrent access from multiple threads without any external synchronization.
 * All methods of this class could potentially throw RocksDBException, which
 * indicates sth wrong at the RocksDB library side and the call failed.
 */
public class RocksDB extends RocksObject {
    public static final byte[] DEFAULT_COLUMN_FAMILY = "default".getBytes();
    public static final int NOT_FOUND = -1;
    // TODO: ------------ start：二次开发代码 --------------- //
    // 当状态获取耗时超过该阈值时将记录日志，小于1表示不记录日志
    protected long logThreshold = PropUtils.getLong("flink.state.log.threshold", 50, 1);
    // 当状态获取耗时超过该阈值时将记录日志的日志条数，小于1表示不限行数
    protected long logThresholdMaxCount = PropUtils.getLong("flink.state.log.threshold.max_count", 300000, 1);
    protected AtomicLong currentLogCount = new AtomicLong();
    protected static Logger logger = LoggerFactory.getLogger(RocksDB.class);

    /**
     * 用于计算状态获取的耗时
     */
    protected void elapsed(long start) {
        long elapsed = System.currentTimeMillis() - start;
        // 当且仅当以下两个条件满足时才会记录耗时日志：
        // 1. 当flink.state.log.threshold配置的阈值大于0时
        // 2. 当flink.state.log.threshold.max_count配置的值小于1时或者当记录的行数小于配置的值时
        if (this.logThreshold > 0 && (this.logThresholdMaxCount < 1 || this.currentLogCount.get() <= this.logThresholdMaxCount)) {
            if (elapsed >= this.logThreshold * 2) {
                logger.warn("RocksDB state get elapsed：{}ms.", elapsed);
                this.currentLogCount.incrementAndGet();
            } else if (elapsed >= this.logThreshold) {
                logger.info("RocksDB state get elapsed：{}ms.", elapsed);
                this.currentLogCount.incrementAndGet();
            }
        }
    }
    // TODO: ------------ end：二次开发代码  --------------- //

    private enum LibraryState {
        NOT_LOADED,
        LOADING,
        LOADED
    }

    private static AtomicReference<LibraryState> libraryLoaded
            = new AtomicReference<>(LibraryState.NOT_LOADED);

    static {
        RocksDB.loadLibrary();
    }

    /**
     * Loads the necessary library files.
     * Calling this method twice will have no effect.
     * By default the method extracts the shared library for loading at
     * java.io.tmpdir, however, you can override this temporary location by
     * setting the environment variable ROCKSDB_SHAREDLIB_DIR.
     */
    public static void loadLibrary() {
        if (libraryLoaded.get() == LibraryState.LOADED) {
            return;
        }

        if (libraryLoaded.compareAndSet(LibraryState.NOT_LOADED,
                LibraryState.LOADING)) {
            final String tmpDir = System.getenv("ROCKSDB_SHAREDLIB_DIR");
            // loading possibly necessary libraries.
            for (final CompressionType compressionType : CompressionType.values()) {
                try {
                    if (compressionType.getLibraryName() != null) {
                        System.loadLibrary(compressionType.getLibraryName());
                    }
                } catch (UnsatisfiedLinkError e) {
                    // since it may be optional, we ignore its loading failure here.
                }
            }
            try {
                NativeLibraryLoader.getInstance().loadLibrary(tmpDir);
            } catch (IOException e) {
                libraryLoaded.set(LibraryState.NOT_LOADED);
                throw new RuntimeException("Unable to load the RocksDB shared library"
                        + e);
            }

            libraryLoaded.set(LibraryState.LOADED);
            return;
        }

        while (libraryLoaded.get() == LibraryState.LOADING) {
            try {
                Thread.sleep(10);
            } catch(final InterruptedException e) {
                //ignore
            }
        }
    }

    /**
     * Tries to load the necessary library files from the given list of
     * directories.
     *
     * @param paths a list of strings where each describes a directory
     *     of a library.
     */
    public static void loadLibrary(final List<String> paths) {
        if (libraryLoaded.get() == LibraryState.LOADED) {
            return;
        }

        if (libraryLoaded.compareAndSet(LibraryState.NOT_LOADED,
                LibraryState.LOADING)) {
            for (final CompressionType compressionType : CompressionType.values()) {
                if (compressionType.equals(CompressionType.NO_COMPRESSION)) {
                    continue;
                }
                for (final String path : paths) {
                    try {
                        System.load(path + "/" + Environment.getSharedLibraryFileName(
                                compressionType.getLibraryName()));
                        break;
                    } catch (UnsatisfiedLinkError e) {
                        // since they are optional, we ignore loading fails.
                    }
                }
            }
            boolean success = false;
            UnsatisfiedLinkError err = null;
            for (final String path : paths) {
                try {
                    System.load(path + "/" +
                            Environment.getJniLibraryFileName("rocksdbjni"));
                    success = true;
                    break;
                } catch (UnsatisfiedLinkError e) {
                    err = e;
                }
            }
            if (!success) {
                libraryLoaded.set(LibraryState.NOT_LOADED);
                throw err;
            }

            libraryLoaded.set(LibraryState.LOADED);
            return;
        }

        while (libraryLoaded.get() == LibraryState.LOADING) {
            try {
                Thread.sleep(10);
            } catch(final InterruptedException e) {
                //ignore
            }
        }
    }

    /**
     * The factory constructor of RocksDB that opens a RocksDB instance given
     * the path to the database using the default options w/ createIfMissing
     * set to true.
     *
     * @param path the path to the rocksdb.
     * @return a {@link RocksDB} instance on success, null if the specified
     *     {@link RocksDB} can not be opened.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     * @see Options#setCreateIfMissing(boolean)
     */
    public static RocksDB open(final String path) throws RocksDBException {
        // This allows to use the rocksjni default Options instead of
        // the c++ one.
        Options options = new Options();
        options.setCreateIfMissing(true);
        return open(options, path);
    }

    /**
     * The factory constructor of RocksDB that opens a RocksDB instance given
     * the path to the database using the specified options and db path and a list
     * of column family names.
     * <p>
     * If opened in read write mode every existing column family name must be
     * passed within the list to this method.</p>
     * <p>
     * If opened in read-only mode only a subset of existing column families must
     * be passed to this method.</p>
     * <p>
     * Options instance *should* not be disposed before all DBs using this options
     * instance have been closed. If user doesn't call options dispose explicitly,
     * then this options instance will be GC'd automatically</p>
     * <p>
     * ColumnFamily handles are disposed when the RocksDB instance is disposed.
     * </p>
     *
     * @param path the path to the rocksdb.
     * @param columnFamilyDescriptors list of column family descriptors
     * @param columnFamilyHandles will be filled with ColumnFamilyHandle instances
     *     on open.
     * @return a {@link RocksDB} instance on success, null if the specified
     *     {@link RocksDB} can not be opened.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     * @see DBOptions#setCreateIfMissing(boolean)
     */
    public static RocksDB open(final String path,
                               final List<ColumnFamilyDescriptor> columnFamilyDescriptors,
                               final List<ColumnFamilyHandle> columnFamilyHandles)
            throws RocksDBException {
        // This allows to use the rocksjni default Options instead of
        // the c++ one.
        DBOptions options = new DBOptions();
        return open(options, path, columnFamilyDescriptors, columnFamilyHandles);
    }

    /**
     * The factory constructor of RocksDB that opens a RocksDB instance given
     * the path to the database using the specified options and db path.
     *
     * <p>
     * Options instance *should* not be disposed before all DBs using this options
     * instance have been closed. If user doesn't call options dispose explicitly,
     * then this options instance will be GC'd automatically.</p>
     * <p>
     * Options instance can be re-used to open multiple DBs if DB statistics is
     * not used. If DB statistics are required, then its recommended to open DB
     * with new Options instance as underlying native statistics instance does not
     * use any locks to prevent concurrent updates.</p>
     *
     * @param options {@link org.rocksdb.Options} instance.
     * @param path the path to the rocksdb.
     * @return a {@link RocksDB} instance on success, null if the specified
     *     {@link RocksDB} can not be opened.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     *
     * @see Options#setCreateIfMissing(boolean)
     */
    public static RocksDB open(final Options options, final String path)
            throws RocksDBException {
        // when non-default Options is used, keeping an Options reference
        // in RocksDB can prevent Java to GC during the life-time of
        // the currently-created RocksDB.
        final RocksDB db = new RocksDB(open(options.nativeHandle_, path));
        db.storeOptionsInstance(options);
        return db;
    }

    /**
     * The factory constructor of RocksDB that opens a RocksDB instance given
     * the path to the database using the specified options and db path and a list
     * of column family names.
     * <p>
     * If opened in read write mode every existing column family name must be
     * passed within the list to this method.</p>
     * <p>
     * If opened in read-only mode only a subset of existing column families must
     * be passed to this method.</p>
     * <p>
     * Options instance *should* not be disposed before all DBs using this options
     * instance have been closed. If user doesn't call options dispose explicitly,
     * then this options instance will be GC'd automatically.</p>
     * <p>
     * Options instance can be re-used to open multiple DBs if DB statistics is
     * not used. If DB statistics are required, then its recommended to open DB
     * with new Options instance as underlying native statistics instance does not
     * use any locks to prevent concurrent updates.</p>
     * <p>
     * ColumnFamily handles are disposed when the RocksDB instance is disposed.
     * </p>
     *
     * @param options {@link org.rocksdb.DBOptions} instance.
     * @param path the path to the rocksdb.
     * @param columnFamilyDescriptors list of column family descriptors
     * @param columnFamilyHandles will be filled with ColumnFamilyHandle instances
     *     on open.
     * @return a {@link RocksDB} instance on success, null if the specified
     *     {@link RocksDB} can not be opened.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     *
     * @see DBOptions#setCreateIfMissing(boolean)
     */
    public static RocksDB open(final DBOptions options, final String path,
                               final List<ColumnFamilyDescriptor> columnFamilyDescriptors,
                               final List<ColumnFamilyHandle> columnFamilyHandles)
            throws RocksDBException {

        final byte[][] cfNames = new byte[columnFamilyDescriptors.size()][];
        final long[] cfOptionHandles = new long[columnFamilyDescriptors.size()];
        for (int i = 0; i < columnFamilyDescriptors.size(); i++) {
            final ColumnFamilyDescriptor cfDescriptor = columnFamilyDescriptors
                    .get(i);
            cfNames[i] = cfDescriptor.columnFamilyName();
            cfOptionHandles[i] = cfDescriptor.columnFamilyOptions().nativeHandle_;
        }

        final long[] handles = open(options.nativeHandle_, path, cfNames,
                cfOptionHandles);
        final RocksDB db = new RocksDB(handles[0]);
        db.storeOptionsInstance(options);

        for (int i = 1; i < handles.length; i++) {
            columnFamilyHandles.add(new ColumnFamilyHandle(db, handles[i]));
        }

        return db;
    }

    /**
     * The factory constructor of RocksDB that opens a RocksDB instance in
     * Read-Only mode given the path to the database using the default
     * options.
     *
     * @param path the path to the RocksDB.
     * @return a {@link RocksDB} instance on success, null if the specified
     *     {@link RocksDB} can not be opened.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public static RocksDB openReadOnly(final String path)
            throws RocksDBException {
        // This allows to use the rocksjni default Options instead of
        // the c++ one.
        Options options = new Options();
        return openReadOnly(options, path);
    }

    /**
     * The factory constructor of RocksDB that opens a RocksDB instance in
     * Read-Only mode given the path to the database using the default
     * options.
     *
     * @param path the path to the RocksDB.
     * @param columnFamilyDescriptors list of column family descriptors
     * @param columnFamilyHandles will be filled with ColumnFamilyHandle instances
     *     on open.
     * @return a {@link RocksDB} instance on success, null if the specified
     *     {@link RocksDB} can not be opened.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public static RocksDB openReadOnly(final String path,
                                       final List<ColumnFamilyDescriptor> columnFamilyDescriptors,
                                       final List<ColumnFamilyHandle> columnFamilyHandles)
            throws RocksDBException {
        // This allows to use the rocksjni default Options instead of
        // the c++ one.
        final DBOptions options = new DBOptions();
        return openReadOnly(options, path, columnFamilyDescriptors,
                columnFamilyHandles);
    }

    /**
     * The factory constructor of RocksDB that opens a RocksDB instance in
     * Read-Only mode given the path to the database using the specified
     * options and db path.
     *
     * Options instance *should* not be disposed before all DBs using this options
     * instance have been closed. If user doesn't call options dispose explicitly,
     * then this options instance will be GC'd automatically.
     *
     * @param options {@link Options} instance.
     * @param path the path to the RocksDB.
     * @return a {@link RocksDB} instance on success, null if the specified
     *     {@link RocksDB} can not be opened.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public static RocksDB openReadOnly(final Options options, final String path)
            throws RocksDBException {
        // when non-default Options is used, keeping an Options reference
        // in RocksDB can prevent Java to GC during the life-time of
        // the currently-created RocksDB.
        final RocksDB db = new RocksDB(openROnly(options.nativeHandle_, path));
        db.storeOptionsInstance(options);
        return db;
    }

    /**
     * The factory constructor of RocksDB that opens a RocksDB instance in
     * Read-Only mode given the path to the database using the specified
     * options and db path.
     *
     * <p>This open method allows to open RocksDB using a subset of available
     * column families</p>
     * <p>Options instance *should* not be disposed before all DBs using this
     * options instance have been closed. If user doesn't call options dispose
     * explicitly,then this options instance will be GC'd automatically.</p>
     *
     * @param options {@link DBOptions} instance.
     * @param path the path to the RocksDB.
     * @param columnFamilyDescriptors list of column family descriptors
     * @param columnFamilyHandles will be filled with ColumnFamilyHandle instances
     *     on open.
     * @return a {@link RocksDB} instance on success, null if the specified
     *     {@link RocksDB} can not be opened.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public static RocksDB openReadOnly(final DBOptions options, final String path,
                                       final List<ColumnFamilyDescriptor> columnFamilyDescriptors,
                                       final List<ColumnFamilyHandle> columnFamilyHandles)
            throws RocksDBException {
        // when non-default Options is used, keeping an Options reference
        // in RocksDB can prevent Java to GC during the life-time of
        // the currently-created RocksDB.

        final byte[][] cfNames = new byte[columnFamilyDescriptors.size()][];
        final long[] cfOptionHandles = new long[columnFamilyDescriptors.size()];
        for (int i = 0; i < columnFamilyDescriptors.size(); i++) {
            final ColumnFamilyDescriptor cfDescriptor = columnFamilyDescriptors
                    .get(i);
            cfNames[i] = cfDescriptor.columnFamilyName();
            cfOptionHandles[i] = cfDescriptor.columnFamilyOptions().nativeHandle_;
        }

        final long[] handles = openROnly(options.nativeHandle_, path, cfNames,
                cfOptionHandles);
        final RocksDB db = new RocksDB(handles[0]);
        db.storeOptionsInstance(options);

        for (int i = 1; i < handles.length; i++) {
            columnFamilyHandles.add(new ColumnFamilyHandle(db, handles[i]));
        }

        return db;
    }
    /**
     * Static method to determine all available column families for a
     * rocksdb database identified by path
     *
     * @param options Options for opening the database
     * @param path Absolute path to rocksdb database
     * @return List&lt;byte[]&gt; List containing the column family names
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public static List<byte[]> listColumnFamilies(final Options options,
                                                  final String path) throws RocksDBException {
        return Arrays.asList(RocksDB.listColumnFamilies(options.nativeHandle_,
                path));
    }

    protected void storeOptionsInstance(DBOptionsInterface options) {
        options_ = options;
    }

    /**
     * Set the database entry for "key" to "value".
     *
     * @param key the specified key to be inserted.
     * @param value the value associated with the specified key.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public void put(final byte[] key, final byte[] value)
            throws RocksDBException {
        put(nativeHandle_, key, 0, key.length, value, 0, value.length);
    }

    /**
     * Set the database entry for "key" to "value" in the specified
     * column family.
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @param key the specified key to be inserted.
     * @param value the value associated with the specified key.
     *
     * throws IllegalArgumentException if column family is not present
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public void put(final ColumnFamilyHandle columnFamilyHandle,
                    final byte[] key, final byte[] value) throws RocksDBException {
        put(nativeHandle_, key, 0, key.length, value, 0, value.length,
                columnFamilyHandle.nativeHandle_);
    }

    /**
     * Set the database entry for "key" to "value".
     *
     * @param writeOpts {@link org.rocksdb.WriteOptions} instance.
     * @param key the specified key to be inserted.
     * @param value the value associated with the specified key.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public void put(final WriteOptions writeOpts, final byte[] key,
                    final byte[] value) throws RocksDBException {
        put(nativeHandle_, writeOpts.nativeHandle_,
                key, 0, key.length, value, 0, value.length);
    }

    /**
     * Set the database entry for "key" to "value" for the specified
     * column family.
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @param writeOpts {@link org.rocksdb.WriteOptions} instance.
     * @param key the specified key to be inserted.
     * @param value the value associated with the specified key.
     *
     * throws IllegalArgumentException if column family is not present
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     * @see IllegalArgumentException
     */
    public void put(final ColumnFamilyHandle columnFamilyHandle,
                    final WriteOptions writeOpts, final byte[] key,
                    final byte[] value) throws RocksDBException {
        put(nativeHandle_, writeOpts.nativeHandle_, key, 0, key.length, value,
                0, value.length, columnFamilyHandle.nativeHandle_);
    }

    /**
     * If the key definitely does not exist in the database, then this method
     * returns false, else true.
     *
     * This check is potentially lighter-weight than invoking DB::Get(). One way
     * to make this lighter weight is to avoid doing any IOs.
     *
     * @param key byte array of a key to search for
     * @param value StringBuilder instance which is a out parameter if a value is
     *    found in block-cache.
     * @return boolean value indicating if key does not exist or might exist.
     */
    public boolean keyMayExist(final byte[] key, final StringBuilder value) {
        return keyMayExist(nativeHandle_, key, 0, key.length, value);
    }

    /**
     * If the key definitely does not exist in the database, then this method
     * returns false, else true.
     *
     * This check is potentially lighter-weight than invoking DB::Get(). One way
     * to make this lighter weight is to avoid doing any IOs.
     *
     * @param columnFamilyHandle {@link ColumnFamilyHandle} instance
     * @param key byte array of a key to search for
     * @param value StringBuilder instance which is a out parameter if a value is
     *    found in block-cache.
     * @return boolean value indicating if key does not exist or might exist.
     */
    public boolean keyMayExist(final ColumnFamilyHandle columnFamilyHandle,
                               final byte[] key, final StringBuilder value) {
        return keyMayExist(nativeHandle_, key, 0, key.length,
                columnFamilyHandle.nativeHandle_, value);
    }

    /**
     * If the key definitely does not exist in the database, then this method
     * returns false, else true.
     *
     * This check is potentially lighter-weight than invoking DB::Get(). One way
     * to make this lighter weight is to avoid doing any IOs.
     *
     * @param readOptions {@link ReadOptions} instance
     * @param key byte array of a key to search for
     * @param value StringBuilder instance which is a out parameter if a value is
     *    found in block-cache.
     * @return boolean value indicating if key does not exist or might exist.
     */
    public boolean keyMayExist(final ReadOptions readOptions,
                               final byte[] key, final StringBuilder value) {
        return keyMayExist(nativeHandle_, readOptions.nativeHandle_,
                key, 0, key.length, value);
    }

    /**
     * If the key definitely does not exist in the database, then this method
     * returns false, else true.
     *
     * This check is potentially lighter-weight than invoking DB::Get(). One way
     * to make this lighter weight is to avoid doing any IOs.
     *
     * @param readOptions {@link ReadOptions} instance
     * @param columnFamilyHandle {@link ColumnFamilyHandle} instance
     * @param key byte array of a key to search for
     * @param value StringBuilder instance which is a out parameter if a value is
     *    found in block-cache.
     * @return boolean value indicating if key does not exist or might exist.
     */
    public boolean keyMayExist(final ReadOptions readOptions,
                               final ColumnFamilyHandle columnFamilyHandle, final byte[] key,
                               final StringBuilder value) {
        return keyMayExist(nativeHandle_, readOptions.nativeHandle_,
                key, 0, key.length, columnFamilyHandle.nativeHandle_,
                value);
    }

    /**
     * Apply the specified updates to the database.
     *
     * @param writeOpts WriteOptions instance
     * @param updates WriteBatch instance
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public void write(final WriteOptions writeOpts, final WriteBatch updates)
            throws RocksDBException {
        write0(nativeHandle_, writeOpts.nativeHandle_, updates.nativeHandle_);
    }

    /**
     * Apply the specified updates to the database.
     *
     * @param writeOpts WriteOptions instance
     * @param updates WriteBatchWithIndex instance
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public void write(final WriteOptions writeOpts,
                      final WriteBatchWithIndex updates) throws RocksDBException {
        write1(nativeHandle_, writeOpts.nativeHandle_, updates.nativeHandle_);
    }

    /**
     * Add merge operand for key/value pair.
     *
     * @param key the specified key to be merged.
     * @param value the value to be merged with the current value for
     * the specified key.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public void merge(final byte[] key, final byte[] value)
            throws RocksDBException {
        merge(nativeHandle_, key, 0, key.length, value, 0, value.length);
    }

    /**
     * Add merge operand for key/value pair in a ColumnFamily.
     *
     * @param columnFamilyHandle {@link ColumnFamilyHandle} instance
     * @param key the specified key to be merged.
     * @param value the value to be merged with the current value for
     * the specified key.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public void merge(final ColumnFamilyHandle columnFamilyHandle,
                      final byte[] key, final byte[] value) throws RocksDBException {
        merge(nativeHandle_, key, 0, key.length, value, 0, value.length,
                columnFamilyHandle.nativeHandle_);
    }

    /**
     * Add merge operand for key/value pair.
     *
     * @param writeOpts {@link WriteOptions} for this write.
     * @param key the specified key to be merged.
     * @param value the value to be merged with the current value for
     * the specified key.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public void merge(final WriteOptions writeOpts, final byte[] key,
                      final byte[] value) throws RocksDBException {
        merge(nativeHandle_, writeOpts.nativeHandle_,
                key, 0, key.length, value, 0, value.length);
    }

    /**
     * Add merge operand for key/value pair.
     *
     * @param columnFamilyHandle {@link ColumnFamilyHandle} instance
     * @param writeOpts {@link WriteOptions} for this write.
     * @param key the specified key to be merged.
     * @param value the value to be merged with the current value for
     * the specified key.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public void merge(final ColumnFamilyHandle columnFamilyHandle,
                      final WriteOptions writeOpts, final byte[] key,
                      final byte[] value) throws RocksDBException {
        merge(nativeHandle_, writeOpts.nativeHandle_,
                key, 0, key.length, value, 0, value.length,
                columnFamilyHandle.nativeHandle_);
    }

    // TODO(AR) we should improve the #get() API, returning -1 (RocksDB.NOT_FOUND) is not very nice
    // when we could communicate better status into, also the C++ code show that -2 could be returned

    /**
     * Get the value associated with the specified key within column family*
     * @param key the key to retrieve the value.
     * @param value the out-value to receive the retrieved value.
     * @return The size of the actual value that matches the specified
     *     {@code key} in byte.  If the return value is greater than the
     *     length of {@code value}, then it indicates that the size of the
     *     input buffer {@code value} is insufficient and partial result will
     *     be returned.  RocksDB.NOT_FOUND will be returned if the value not
     *     found.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public int get(final byte[] key, final byte[] value) throws RocksDBException {
        return get(nativeHandle_, key, 0, key.length, value, 0, value.length);
    }

    /**
     * Get the value associated with the specified key within column family.
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @param key the key to retrieve the value.
     * @param value the out-value to receive the retrieved value.
     * @return The size of the actual value that matches the specified
     *     {@code key} in byte.  If the return value is greater than the
     *     length of {@code value}, then it indicates that the size of the
     *     input buffer {@code value} is insufficient and partial result will
     *     be returned.  RocksDB.NOT_FOUND will be returned if the value not
     *     found.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public int get(final ColumnFamilyHandle columnFamilyHandle, final byte[] key,
                   final byte[] value) throws RocksDBException, IllegalArgumentException {
        return get(nativeHandle_, key, 0, key.length, value, 0, value.length,
                columnFamilyHandle.nativeHandle_);
    }

    /**
     * Get the value associated with the specified key.
     *
     * @param opt {@link org.rocksdb.ReadOptions} instance.
     * @param key the key to retrieve the value.
     * @param value the out-value to receive the retrieved value.
     * @return The size of the actual value that matches the specified
     *     {@code key} in byte.  If the return value is greater than the
     *     length of {@code value}, then it indicates that the size of the
     *     input buffer {@code value} is insufficient and partial result will
     *     be returned.  RocksDB.NOT_FOUND will be returned if the value not
     *     found.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public int get(final ReadOptions opt, final byte[] key,
                   final byte[] value) throws RocksDBException {
        return get(nativeHandle_, opt.nativeHandle_,
                key, 0, key.length, value, 0, value.length);
    }
    /**
     * Get the value associated with the specified key within column family.
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @param opt {@link org.rocksdb.ReadOptions} instance.
     * @param key the key to retrieve the value.
     * @param value the out-value to receive the retrieved value.
     * @return The size of the actual value that matches the specified
     *     {@code key} in byte.  If the return value is greater than the
     *     length of {@code value}, then it indicates that the size of the
     *     input buffer {@code value} is insufficient and partial result will
     *     be returned.  RocksDB.NOT_FOUND will be returned if the value not
     *     found.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public int get(final ColumnFamilyHandle columnFamilyHandle,
                   final ReadOptions opt, final byte[] key, final byte[] value)
            throws RocksDBException {
        return get(nativeHandle_, opt.nativeHandle_, key, 0, key.length, value,
                0, value.length, columnFamilyHandle.nativeHandle_);
    }

    /**
     * The simplified version of get which returns a new byte array storing
     * the value associated with the specified input key if any.  null will be
     * returned if the specified key is not found.
     *
     * @param key the key retrieve the value.
     * @return a byte array storing the value associated with the input key if
     *     any.  null if it does not find the specified key.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public byte[] get(final byte[] key) throws RocksDBException {
        return get(nativeHandle_, key, 0, key.length);
    }

    /**
     * The simplified version of get which returns a new byte array storing
     * the value associated with the specified input key if any.  null will be
     * returned if the specified key is not found.
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @param key the key retrieve the value.
     * @return a byte array storing the value associated with the input key if
     *     any.  null if it does not find the specified key.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public byte[] get(final ColumnFamilyHandle columnFamilyHandle,
                      final byte[] key) throws RocksDBException {
        // TODO: ------------ start：二次开发代码 --------------- //
        long start = System.currentTimeMillis();
        byte[] state = get(nativeHandle_, key, 0, key.length,
                columnFamilyHandle.nativeHandle_);
        this.elapsed(start);
        // TODO: ------------ end：二次开发代码 --------------- //
        return state;
    }

    /**
     * The simplified version of get which returns a new byte array storing
     * the value associated with the specified input key if any.  null will be
     * returned if the specified key is not found.
     *
     * @param key the key retrieve the value.
     * @param opt Read options.
     * @return a byte array storing the value associated with the input key if
     *     any.  null if it does not find the specified key.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public byte[] get(final ReadOptions opt, final byte[] key)
            throws RocksDBException {
        return get(nativeHandle_, opt.nativeHandle_, key, 0, key.length);
    }

    /**
     * The simplified version of get which returns a new byte array storing
     * the value associated with the specified input key if any.  null will be
     * returned if the specified key is not found.
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @param key the key retrieve the value.
     * @param opt Read options.
     * @return a byte array storing the value associated with the input key if
     *     any.  null if it does not find the specified key.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public byte[] get(final ColumnFamilyHandle columnFamilyHandle,
                      final ReadOptions opt, final byte[] key) throws RocksDBException {
        return get(nativeHandle_, opt.nativeHandle_, key, 0, key.length,
                columnFamilyHandle.nativeHandle_);
    }

    /**
     * Returns a map of keys for which values were found in DB.
     *
     * @param keys List of keys for which values need to be retrieved.
     * @return Map where key of map is the key passed by user and value for map
     * entry is the corresponding value in DB.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public Map<byte[], byte[]> multiGet(final List<byte[]> keys)
            throws RocksDBException {
        assert(keys.size() != 0);

        final byte[][] keysArray = keys.toArray(new byte[keys.size()][]);
        final int keyOffsets[] = new int[keysArray.length];
        final int keyLengths[] = new int[keysArray.length];
        for(int i = 0; i < keyLengths.length; i++) {
            keyLengths[i] = keysArray[i].length;
        }

        final byte[][] values = multiGet(nativeHandle_, keysArray, keyOffsets,
                keyLengths);

        final Map<byte[], byte[]> keyValueMap =
                new HashMap<>(computeCapacityHint(values.length));
        for(int i = 0; i < values.length; i++) {
            if(values[i] == null) {
                continue;
            }

            keyValueMap.put(keys.get(i), values[i]);
        }

        return keyValueMap;
    }

    private static int computeCapacityHint(final int estimatedNumberOfItems) {
        // Default load factor for HashMap is 0.75, so N * 1.5 will be at the load
        // limit. We add +1 for a buffer.
        return (int)Math.ceil(estimatedNumberOfItems * 1.5 + 1.0);
    }

    /**
     * Returns a map of keys for which values were found in DB.
     * <p>
     * Note: Every key needs to have a related column family name in
     * {@code columnFamilyHandleList}.
     * </p>
     *
     * @param columnFamilyHandleList {@link java.util.List} containing
     *     {@link org.rocksdb.ColumnFamilyHandle} instances.
     * @param keys List of keys for which values need to be retrieved.
     * @return Map where key of map is the key passed by user and value for map
     * entry is the corresponding value in DB.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     * @throws IllegalArgumentException thrown if the size of passed keys is not
     *    equal to the amount of passed column family handles.
     */
    public Map<byte[], byte[]> multiGet(
            final List<ColumnFamilyHandle> columnFamilyHandleList,
            final List<byte[]> keys) throws RocksDBException,
            IllegalArgumentException {
        assert(keys.size() != 0);
        // Check if key size equals cfList size. If not a exception must be
        // thrown. If not a Segmentation fault happens.
        if (keys.size() != columnFamilyHandleList.size()) {
            throw new IllegalArgumentException(
                    "For each key there must be a ColumnFamilyHandle.");
        }
        final long[] cfHandles = new long[columnFamilyHandleList.size()];
        for (int i = 0; i < columnFamilyHandleList.size(); i++) {
            cfHandles[i] = columnFamilyHandleList.get(i).nativeHandle_;
        }

        final byte[][] keysArray = keys.toArray(new byte[keys.size()][]);
        final int keyOffsets[] = new int[keysArray.length];
        final int keyLengths[] = new int[keysArray.length];
        for(int i = 0; i < keyLengths.length; i++) {
            keyLengths[i] = keysArray[i].length;
        }

        final byte[][] values = multiGet(nativeHandle_, keysArray, keyOffsets,
                keyLengths, cfHandles);

        final Map<byte[], byte[]> keyValueMap =
                new HashMap<>(computeCapacityHint(values.length));
        for(int i = 0; i < values.length; i++) {
            if (values[i] == null) {
                continue;
            }
            keyValueMap.put(keys.get(i), values[i]);
        }
        return keyValueMap;
    }

    /**
     * Returns a map of keys for which values were found in DB.
     *
     * @param opt Read options.
     * @param keys of keys for which values need to be retrieved.
     * @return Map where key of map is the key passed by user and value for map
     * entry is the corresponding value in DB.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public Map<byte[], byte[]> multiGet(final ReadOptions opt,
                                        final List<byte[]> keys) throws RocksDBException {
        assert(keys.size() != 0);

        final byte[][] keysArray = keys.toArray(new byte[keys.size()][]);
        final int keyOffsets[] = new int[keysArray.length];
        final int keyLengths[] = new int[keysArray.length];
        for(int i = 0; i < keyLengths.length; i++) {
            keyLengths[i] = keysArray[i].length;
        }

        final byte[][] values = multiGet(nativeHandle_, opt.nativeHandle_,
                keysArray, keyOffsets, keyLengths);

        final Map<byte[], byte[]> keyValueMap =
                new HashMap<>(computeCapacityHint(values.length));
        for(int i = 0; i < values.length; i++) {
            if(values[i] == null) {
                continue;
            }

            keyValueMap.put(keys.get(i), values[i]);
        }

        return keyValueMap;
    }

    /**
     * Returns a map of keys for which values were found in DB.
     * <p>
     * Note: Every key needs to have a related column family name in
     * {@code columnFamilyHandleList}.
     * </p>
     *
     * @param opt Read options.
     * @param columnFamilyHandleList {@link java.util.List} containing
     *     {@link org.rocksdb.ColumnFamilyHandle} instances.
     * @param keys of keys for which values need to be retrieved.
     * @return Map where key of map is the key passed by user and value for map
     * entry is the corresponding value in DB.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     * @throws IllegalArgumentException thrown if the size of passed keys is not
     *    equal to the amount of passed column family handles.
     */
    public Map<byte[], byte[]> multiGet(final ReadOptions opt,
                                        final List<ColumnFamilyHandle> columnFamilyHandleList,
                                        final List<byte[]> keys) throws RocksDBException {
        assert(keys.size() != 0);
        // Check if key size equals cfList size. If not a exception must be
        // thrown. If not a Segmentation fault happens.
        if (keys.size()!=columnFamilyHandleList.size()){
            throw new IllegalArgumentException(
                    "For each key there must be a ColumnFamilyHandle.");
        }
        final long[] cfHandles = new long[columnFamilyHandleList.size()];
        for (int i = 0; i < columnFamilyHandleList.size(); i++) {
            cfHandles[i] = columnFamilyHandleList.get(i).nativeHandle_;
        }

        final byte[][] keysArray = keys.toArray(new byte[keys.size()][]);
        final int keyOffsets[] = new int[keysArray.length];
        final int keyLengths[] = new int[keysArray.length];
        for(int i = 0; i < keyLengths.length; i++) {
            keyLengths[i] = keysArray[i].length;
        }

        final byte[][] values = multiGet(nativeHandle_, opt.nativeHandle_,
                keysArray, keyOffsets, keyLengths, cfHandles);

        final Map<byte[], byte[]> keyValueMap
                = new HashMap<>(computeCapacityHint(values.length));
        for(int i = 0; i < values.length; i++) {
            if(values[i] == null) {
                continue;
            }
            keyValueMap.put(keys.get(i), values[i]);
        }

        return keyValueMap;
    }

    /**
     * Remove the database entry (if any) for "key".  Returns OK on
     * success, and a non-OK status on error.  It is not an error if "key"
     * did not exist in the database.
     *
     * @param key Key to delete within database
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     *
     * @deprecated Use {@link #delete(byte[])}
     */
    @Deprecated
    public void remove(final byte[] key) throws RocksDBException {
        delete(key);
    }

    /**
     * Delete the database entry (if any) for "key".  Returns OK on
     * success, and a non-OK status on error.  It is not an error if "key"
     * did not exist in the database.
     *
     * @param key Key to delete within database
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public void delete(final byte[] key) throws RocksDBException {
        delete(nativeHandle_, key, 0, key.length);
    }

    /**
     * Remove the database entry (if any) for "key".  Returns OK on
     * success, and a non-OK status on error.  It is not an error if "key"
     * did not exist in the database.
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @param key Key to delete within database
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     *
     * @deprecated Use {@link #delete(ColumnFamilyHandle, byte[])}
     */
    @Deprecated
    public void remove(final ColumnFamilyHandle columnFamilyHandle,
                       final byte[] key) throws RocksDBException {
        delete(columnFamilyHandle, key);
    }

    /**
     * Delete the database entry (if any) for "key".  Returns OK on
     * success, and a non-OK status on error.  It is not an error if "key"
     * did not exist in the database.
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @param key Key to delete within database
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public void delete(final ColumnFamilyHandle columnFamilyHandle,
                       final byte[] key) throws RocksDBException {
        delete(nativeHandle_, key, 0, key.length, columnFamilyHandle.nativeHandle_);
    }

    /**
     * Remove the database entry (if any) for "key".  Returns OK on
     * success, and a non-OK status on error.  It is not an error if "key"
     * did not exist in the database.
     *
     * @param writeOpt WriteOptions to be used with delete operation
     * @param key Key to delete within database
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     *
     * @deprecated Use {@link #delete(WriteOptions, byte[])}
     */
    @Deprecated
    public void remove(final WriteOptions writeOpt, final byte[] key)
            throws RocksDBException {
        delete(writeOpt, key);
    }

    /**
     * Delete the database entry (if any) for "key".  Returns OK on
     * success, and a non-OK status on error.  It is not an error if "key"
     * did not exist in the database.
     *
     * @param writeOpt WriteOptions to be used with delete operation
     * @param key Key to delete within database
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public void delete(final WriteOptions writeOpt, final byte[] key)
            throws RocksDBException {
        delete(nativeHandle_, writeOpt.nativeHandle_, key, 0, key.length);
    }

    /**
     * Remove the database entry (if any) for "key".  Returns OK on
     * success, and a non-OK status on error.  It is not an error if "key"
     * did not exist in the database.
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @param writeOpt WriteOptions to be used with delete operation
     * @param key Key to delete within database
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     *
     * @deprecated Use {@link #delete(ColumnFamilyHandle, WriteOptions, byte[])}
     */
    @Deprecated
    public void remove(final ColumnFamilyHandle columnFamilyHandle,
                       final WriteOptions writeOpt, final byte[] key)
            throws RocksDBException {
        delete(columnFamilyHandle, writeOpt, key);
    }

    /**
     * Delete the database entry (if any) for "key".  Returns OK on
     * success, and a non-OK status on error.  It is not an error if "key"
     * did not exist in the database.
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @param writeOpt WriteOptions to be used with delete operation
     * @param key Key to delete within database
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public void delete(final ColumnFamilyHandle columnFamilyHandle,
                       final WriteOptions writeOpt, final byte[] key)
            throws RocksDBException {
        delete(nativeHandle_, writeOpt.nativeHandle_, key, 0, key.length,
                columnFamilyHandle.nativeHandle_);
    }

    /**
     * Remove the database entry for {@code key}. Requires that the key exists
     * and was not overwritten. It is not an error if the key did not exist
     * in the database.
     *
     * If a key is overwritten (by calling {@link #put(byte[], byte[])} multiple
     * times), then the result of calling SingleDelete() on this key is undefined.
     * SingleDelete() only behaves correctly if there has been only one Put()
     * for this key since the previous call to SingleDelete() for this key.
     *
     * This feature is currently an experimental performance optimization
     * for a very specific workload. It is up to the caller to ensure that
     * SingleDelete is only used for a key that is not deleted using Delete() or
     * written using Merge(). Mixing SingleDelete operations with Deletes and
     * Merges can result in undefined behavior.
     *
     * @param key Key to delete within database
     *
     * @throws RocksDBException thrown if error happens in underlying
     *     native library.
     */
    @Experimental("Performance optimization for a very specific workload")
    public void singleDelete(final byte[] key) throws RocksDBException {
        singleDelete(nativeHandle_, key, key.length);
    }

    /**
     * Remove the database entry for {@code key}. Requires that the key exists
     * and was not overwritten. It is not an error if the key did not exist
     * in the database.
     *
     * If a key is overwritten (by calling {@link #put(byte[], byte[])} multiple
     * times), then the result of calling SingleDelete() on this key is undefined.
     * SingleDelete() only behaves correctly if there has been only one Put()
     * for this key since the previous call to SingleDelete() for this key.
     *
     * This feature is currently an experimental performance optimization
     * for a very specific workload. It is up to the caller to ensure that
     * SingleDelete is only used for a key that is not deleted using Delete() or
     * written using Merge(). Mixing SingleDelete operations with Deletes and
     * Merges can result in undefined behavior.
     *
     * @param columnFamilyHandle The column family to delete the key from
     * @param key Key to delete within database
     *
     * @throws RocksDBException thrown if error happens in underlying
     *     native library.
     */
    @Experimental("Performance optimization for a very specific workload")
    public void singleDelete(final ColumnFamilyHandle columnFamilyHandle,
                             final byte[] key) throws RocksDBException {
        singleDelete(nativeHandle_, key, key.length,
                columnFamilyHandle.nativeHandle_);
    }

    /**
     * Remove the database entry for {@code key}. Requires that the key exists
     * and was not overwritten. It is not an error if the key did not exist
     * in the database.
     *
     * If a key is overwritten (by calling {@link #put(byte[], byte[])} multiple
     * times), then the result of calling SingleDelete() on this key is undefined.
     * SingleDelete() only behaves correctly if there has been only one Put()
     * for this key since the previous call to SingleDelete() for this key.
     *
     * This feature is currently an experimental performance optimization
     * for a very specific workload. It is up to the caller to ensure that
     * SingleDelete is only used for a key that is not deleted using Delete() or
     * written using Merge(). Mixing SingleDelete operations with Deletes and
     * Merges can result in undefined behavior.
     *
     * Note: consider setting {@link WriteOptions#setSync(boolean)} true.
     *
     * @param writeOpt Write options for the delete
     * @param key Key to delete within database
     *
     * @throws RocksDBException thrown if error happens in underlying
     *     native library.
     */
    @Experimental("Performance optimization for a very specific workload")
    public void singleDelete(final WriteOptions writeOpt, final byte[] key)
            throws RocksDBException {
        singleDelete(nativeHandle_, writeOpt.nativeHandle_, key, key.length);
    }

    /**
     * Remove the database entry for {@code key}. Requires that the key exists
     * and was not overwritten. It is not an error if the key did not exist
     * in the database.
     *
     * If a key is overwritten (by calling {@link #put(byte[], byte[])} multiple
     * times), then the result of calling SingleDelete() on this key is undefined.
     * SingleDelete() only behaves correctly if there has been only one Put()
     * for this key since the previous call to SingleDelete() for this key.
     *
     * This feature is currently an experimental performance optimization
     * for a very specific workload. It is up to the caller to ensure that
     * SingleDelete is only used for a key that is not deleted using Delete() or
     * written using Merge(). Mixing SingleDelete operations with Deletes and
     * Merges can result in undefined behavior.
     *
     * Note: consider setting {@link WriteOptions#setSync(boolean)} true.
     *
     * @param columnFamilyHandle The column family to delete the key from
     * @param writeOpt Write options for the delete
     * @param key Key to delete within database
     *
     * @throws RocksDBException thrown if error happens in underlying
     *     native library.
     */
    @Experimental("Performance optimization for a very specific workload")
    public void singleDelete(final ColumnFamilyHandle columnFamilyHandle,
                             final WriteOptions writeOpt, final byte[] key) throws RocksDBException {
        singleDelete(nativeHandle_, writeOpt.nativeHandle_, key, key.length,
                columnFamilyHandle.nativeHandle_);
    }

    /**
     * DB implements can export properties about their state
     * via this method on a per column family level.
     *
     * <p>If {@code property} is a valid property understood by this DB
     * implementation, fills {@code value} with its current value and
     * returns true. Otherwise returns false.</p>
     *
     * <p>Valid property names include:
     * <ul>
     * <li>"rocksdb.num-files-at-level&lt;N&gt;" - return the number of files at
     * level &lt;N&gt;, where &lt;N&gt; is an ASCII representation of a level
     * number (e.g. "0").</li>
     * <li>"rocksdb.stats" - returns a multi-line string that describes statistics
     *     about the internal operation of the DB.</li>
     * <li>"rocksdb.sstables" - returns a multi-line string that describes all
     *    of the sstables that make up the db contents.</li>
     * </ul>
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @param property to be fetched. See above for examples
     * @return property value
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public String getProperty(final ColumnFamilyHandle columnFamilyHandle,
                              final String property) throws RocksDBException {
        return getProperty0(nativeHandle_, columnFamilyHandle.nativeHandle_,
                property, property.length());
    }

    /**
     * Removes the database entries in the range ["beginKey", "endKey"), i.e.,
     * including "beginKey" and excluding "endKey". a non-OK status on error. It
     * is not an error if no keys exist in the range ["beginKey", "endKey").
     *
     * Delete the database entry (if any) for "key". Returns OK on success, and a
     * non-OK status on error. It is not an error if "key" did not exist in the
     * database.
     *
     * @param beginKey
     *          First key to delete within database (included)
     * @param endKey
     *          Last key to delete within database (excluded)
     *
     * @throws RocksDBException
     *           thrown if error happens in underlying native library.
     */
    public void deleteRange(final byte[] beginKey, final byte[] endKey) throws RocksDBException {
        deleteRange(nativeHandle_, beginKey, 0, beginKey.length, endKey, 0, endKey.length);
    }

    /**
     * Removes the database entries in the range ["beginKey", "endKey"), i.e.,
     * including "beginKey" and excluding "endKey". a non-OK status on error. It
     * is not an error if no keys exist in the range ["beginKey", "endKey").
     *
     * Delete the database entry (if any) for "key". Returns OK on success, and a
     * non-OK status on error. It is not an error if "key" did not exist in the
     * database.
     *
     * @param columnFamilyHandle
     *          {@link org.rocksdb.ColumnFamilyHandle} instance
     * @param beginKey
     *          First key to delete within database (included)
     * @param endKey
     *          Last key to delete within database (excluded)
     *
     * @throws RocksDBException
     *           thrown if error happens in underlying native library.
     */
    public void deleteRange(final ColumnFamilyHandle columnFamilyHandle, final byte[] beginKey,
                            final byte[] endKey) throws RocksDBException {
        deleteRange(nativeHandle_, beginKey, 0, beginKey.length, endKey, 0, endKey.length,
                columnFamilyHandle.nativeHandle_);
    }

    /**
     * Removes the database entries in the range ["beginKey", "endKey"), i.e.,
     * including "beginKey" and excluding "endKey". a non-OK status on error. It
     * is not an error if no keys exist in the range ["beginKey", "endKey").
     *
     * Delete the database entry (if any) for "key". Returns OK on success, and a
     * non-OK status on error. It is not an error if "key" did not exist in the
     * database.
     *
     * @param writeOpt
     *          WriteOptions to be used with delete operation
     * @param beginKey
     *          First key to delete within database (included)
     * @param endKey
     *          Last key to delete within database (excluded)
     *
     * @throws RocksDBException
     *           thrown if error happens in underlying native library.
     */
    public void deleteRange(final WriteOptions writeOpt, final byte[] beginKey, final byte[] endKey)
            throws RocksDBException {
        deleteRange(nativeHandle_, writeOpt.nativeHandle_, beginKey, 0, beginKey.length, endKey, 0,
                endKey.length);
    }

    /**
     * Removes the database entries in the range ["beginKey", "endKey"), i.e.,
     * including "beginKey" and excluding "endKey". a non-OK status on error. It
     * is not an error if no keys exist in the range ["beginKey", "endKey").
     *
     * Delete the database entry (if any) for "key". Returns OK on success, and a
     * non-OK status on error. It is not an error if "key" did not exist in the
     * database.
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @param writeOpt
     *          WriteOptions to be used with delete operation
     * @param beginKey
     *          First key to delete within database (included)
     * @param endKey
     *          Last key to delete within database (excluded)
     *
     * @throws RocksDBException
     *           thrown if error happens in underlying native library.
     */
    public void deleteRange(final ColumnFamilyHandle columnFamilyHandle, final WriteOptions writeOpt,
                            final byte[] beginKey, final byte[] endKey) throws RocksDBException {
        deleteRange(nativeHandle_, writeOpt.nativeHandle_, beginKey, 0, beginKey.length, endKey, 0,
                endKey.length, columnFamilyHandle.nativeHandle_);
    }

    /**
     * DB implementations can export properties about their state
     * via this method.  If "property" is a valid property understood by this
     * DB implementation, fills "*value" with its current value and returns
     * true.  Otherwise returns false.
     *
     * <p>Valid property names include:
     * <ul>
     * <li>"rocksdb.num-files-at-level&lt;N&gt;" - return the number of files at
     * level &lt;N&gt;, where &lt;N&gt; is an ASCII representation of a level
     * number (e.g. "0").</li>
     * <li>"rocksdb.stats" - returns a multi-line string that describes statistics
     *     about the internal operation of the DB.</li>
     * <li>"rocksdb.sstables" - returns a multi-line string that describes all
     *    of the sstables that make up the db contents.</li>
     *</ul>
     *
     * @param property to be fetched. See above for examples
     * @return property value
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public String getProperty(final String property) throws RocksDBException {
        return getProperty0(nativeHandle_, property, property.length());
    }

    /**
     * <p> Similar to GetProperty(), but only works for a subset of properties
     * whose return value is a numerical value. Return the value as long.</p>
     *
     * <p><strong>Note</strong>: As the returned property is of type
     * {@code uint64_t} on C++ side the returning value can be negative
     * because Java supports in Java 7 only signed long values.</p>
     *
     * <p><strong>Java 7</strong>: To mitigate the problem of the non
     * existent unsigned long tpye, values should be encapsulated using
     * {@link java.math.BigInteger} to reflect the correct value. The correct
     * behavior is guaranteed if {@code 2^64} is added to negative values.</p>
     *
     * <p><strong>Java 8</strong>: In Java 8 the value should be treated as
     * unsigned long using provided methods of type {@link Long}.</p>
     *
     * @param property to be fetched.
     *
     * @return numerical property value.
     *
     * @throws RocksDBException if an error happens in the underlying native code.
     */
    public long getLongProperty(final String property) throws RocksDBException {
        return getLongProperty(nativeHandle_, property, property.length());
    }

    /**
     * <p> Similar to GetProperty(), but only works for a subset of properties
     * whose return value is a numerical value. Return the value as long.</p>
     *
     * <p><strong>Note</strong>: As the returned property is of type
     * {@code uint64_t} on C++ side the returning value can be negative
     * because Java supports in Java 7 only signed long values.</p>
     *
     * <p><strong>Java 7</strong>: To mitigate the problem of the non
     * existent unsigned long tpye, values should be encapsulated using
     * {@link java.math.BigInteger} to reflect the correct value. The correct
     * behavior is guaranteed if {@code 2^64} is added to negative values.</p>
     *
     * <p><strong>Java 8</strong>: In Java 8 the value should be treated as
     * unsigned long using provided methods of type {@link Long}.</p>
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @param property to be fetched.
     *
     * @return numerical property value
     *
     * @throws RocksDBException if an error happens in the underlying native code.
     */
    public long getLongProperty(final ColumnFamilyHandle columnFamilyHandle,
                                final String property) throws RocksDBException {
        return getLongProperty(nativeHandle_, columnFamilyHandle.nativeHandle_,
                property, property.length());
    }

    /**
     * <p> Return sum of the getLongProperty of all the column families</p>
     *
     * <p><strong>Note</strong>: As the returned property is of type
     * {@code uint64_t} on C++ side the returning value can be negative
     * because Java supports in Java 7 only signed long values.</p>
     *
     * <p><strong>Java 7</strong>: To mitigate the problem of the non
     * existent unsigned long tpye, values should be encapsulated using
     * {@link java.math.BigInteger} to reflect the correct value. The correct
     * behavior is guaranteed if {@code 2^64} is added to negative values.</p>
     *
     * <p><strong>Java 8</strong>: In Java 8 the value should be treated as
     * unsigned long using provided methods of type {@link Long}.</p>
     *
     * @param property to be fetched.
     *
     * @return numerical property value
     *
     * @throws RocksDBException if an error happens in the underlying native code.
     */
    public long getAggregatedLongProperty(final String property) throws RocksDBException {
        return getAggregatedLongProperty(nativeHandle_, property, property.length());
    }

    /**
     * <p>Return a heap-allocated iterator over the contents of the
     * database. The result of newIterator() is initially invalid
     * (caller must call one of the Seek methods on the iterator
     * before using it).</p>
     *
     * <p>Caller should close the iterator when it is no longer needed.
     * The returned iterator should be closed before this db is closed.
     * </p>
     *
     * @return instance of iterator object.
     */
    public RocksIterator newIterator() {
        return new RocksIterator(this, iterator(nativeHandle_));
    }

    /**
     * <p>Return a heap-allocated iterator over the contents of the
     * database. The result of newIterator() is initially invalid
     * (caller must call one of the Seek methods on the iterator
     * before using it).</p>
     *
     * <p>Caller should close the iterator when it is no longer needed.
     * The returned iterator should be closed before this db is closed.
     * </p>
     *
     * @param readOptions {@link ReadOptions} instance.
     * @return instance of iterator object.
     */
    public RocksIterator newIterator(final ReadOptions readOptions) {
        return new RocksIterator(this, iterator(nativeHandle_,
                readOptions.nativeHandle_));
    }

    /**
     * <p>Return a handle to the current DB state. Iterators created with
     * this handle will all observe a stable snapshot of the current DB
     * state. The caller must call ReleaseSnapshot(result) when the
     * snapshot is no longer needed.</p>
     *
     * <p>nullptr will be returned if the DB fails to take a snapshot or does
     * not support snapshot.</p>
     *
     * @return Snapshot {@link Snapshot} instance
     */
    public Snapshot getSnapshot() {
        long snapshotHandle = getSnapshot(nativeHandle_);
        if (snapshotHandle != 0) {
            return new Snapshot(snapshotHandle);
        }
        return null;
    }

    /**
     * Release a previously acquired snapshot.  The caller must not
     * use "snapshot" after this call.
     *
     * @param snapshot {@link Snapshot} instance
     */
    public void releaseSnapshot(final Snapshot snapshot) {
        if (snapshot != null) {
            releaseSnapshot(nativeHandle_, snapshot.nativeHandle_);
        }
    }

    /**
     * <p>Return a heap-allocated iterator over the contents of the
     * database. The result of newIterator() is initially invalid
     * (caller must call one of the Seek methods on the iterator
     * before using it).</p>
     *
     * <p>Caller should close the iterator when it is no longer needed.
     * The returned iterator should be closed before this db is closed.
     * </p>
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @return instance of iterator object.
     */
    public RocksIterator newIterator(
            final ColumnFamilyHandle columnFamilyHandle) {
        return new RocksIterator(this, iteratorCF(nativeHandle_,
                columnFamilyHandle.nativeHandle_));
    }

    /**
     * <p>Return a heap-allocated iterator over the contents of the
     * database. The result of newIterator() is initially invalid
     * (caller must call one of the Seek methods on the iterator
     * before using it).</p>
     *
     * <p>Caller should close the iterator when it is no longer needed.
     * The returned iterator should be closed before this db is closed.
     * </p>
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     * @param readOptions {@link ReadOptions} instance.
     * @return instance of iterator object.
     */
    public RocksIterator newIterator(final ColumnFamilyHandle columnFamilyHandle,
                                     final ReadOptions readOptions) {
        return new RocksIterator(this, iteratorCF(nativeHandle_,
                columnFamilyHandle.nativeHandle_, readOptions.nativeHandle_));
    }

    /**
     * Returns iterators from a consistent database state across multiple
     * column families. Iterators are heap allocated and need to be deleted
     * before the db is deleted
     *
     * @param columnFamilyHandleList {@link java.util.List} containing
     *     {@link org.rocksdb.ColumnFamilyHandle} instances.
     * @return {@link java.util.List} containing {@link org.rocksdb.RocksIterator}
     *     instances
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public List<RocksIterator> newIterators(
            final List<ColumnFamilyHandle> columnFamilyHandleList)
            throws RocksDBException {
        return newIterators(columnFamilyHandleList, new ReadOptions());
    }

    /**
     * Returns iterators from a consistent database state across multiple
     * column families. Iterators are heap allocated and need to be deleted
     * before the db is deleted
     *
     * @param columnFamilyHandleList {@link java.util.List} containing
     *     {@link org.rocksdb.ColumnFamilyHandle} instances.
     * @param readOptions {@link ReadOptions} instance.
     * @return {@link java.util.List} containing {@link org.rocksdb.RocksIterator}
     *     instances
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public List<RocksIterator> newIterators(
            final List<ColumnFamilyHandle> columnFamilyHandleList,
            final ReadOptions readOptions) throws RocksDBException {

        final long[] columnFamilyHandles = new long[columnFamilyHandleList.size()];
        for (int i = 0; i < columnFamilyHandleList.size(); i++) {
            columnFamilyHandles[i] = columnFamilyHandleList.get(i).nativeHandle_;
        }

        final long[] iteratorRefs = iterators(nativeHandle_, columnFamilyHandles,
                readOptions.nativeHandle_);

        final List<RocksIterator> iterators = new ArrayList<>(
                columnFamilyHandleList.size());
        for (int i=0; i<columnFamilyHandleList.size(); i++){
            iterators.add(new RocksIterator(this, iteratorRefs[i]));
        }
        return iterators;
    }

    /**
     * Gets the handle for the default column family
     *
     * @return The handle of the default column family
     */
    public ColumnFamilyHandle getDefaultColumnFamily() {
        final ColumnFamilyHandle cfHandle = new ColumnFamilyHandle(this,
                getDefaultColumnFamily(nativeHandle_));
        cfHandle.disOwnNativeHandle();
        return cfHandle;
    }

    /**
     * Creates a new column family with the name columnFamilyName and
     * allocates a ColumnFamilyHandle within an internal structure.
     * The ColumnFamilyHandle is automatically disposed with DB disposal.
     *
     * @param columnFamilyDescriptor column family to be created.
     * @return {@link org.rocksdb.ColumnFamilyHandle} instance.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public ColumnFamilyHandle createColumnFamily(
            final ColumnFamilyDescriptor columnFamilyDescriptor)
            throws RocksDBException {
        return new ColumnFamilyHandle(this, createColumnFamily(nativeHandle_,
                columnFamilyDescriptor.columnFamilyName(),
                columnFamilyDescriptor.columnFamilyOptions().nativeHandle_));
    }

    /**
     * Drops the column family identified by columnFamilyName. Internal
     * handles to this column family will be disposed. If the column family
     * is not known removal will fail.
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public void dropColumnFamily(final ColumnFamilyHandle columnFamilyHandle)
            throws RocksDBException, IllegalArgumentException {
        // throws RocksDBException if something goes wrong
        dropColumnFamily(nativeHandle_, columnFamilyHandle.nativeHandle_);
        // After the drop the native handle is not valid anymore
        columnFamilyHandle.disOwnNativeHandle();
    }

    /**
     * <p>Flush all memory table data.</p>
     *
     * <p>Note: it must be ensured that the FlushOptions instance
     * is not GC'ed before this method finishes. If the wait parameter is
     * set to false, flush processing is asynchronous.</p>
     *
     * @param flushOptions {@link org.rocksdb.FlushOptions} instance.
     * @throws RocksDBException thrown if an error occurs within the native
     *     part of the library.
     */
    public void flush(final FlushOptions flushOptions)
            throws RocksDBException {
        flush(nativeHandle_, flushOptions.nativeHandle_);
    }

    /**
     * <p>Flush all memory table data.</p>
     *
     * <p>Note: it must be ensured that the FlushOptions instance
     * is not GC'ed before this method finishes. If the wait parameter is
     * set to false, flush processing is asynchronous.</p>
     *
     * @param flushOptions {@link org.rocksdb.FlushOptions} instance.
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle} instance.
     * @throws RocksDBException thrown if an error occurs within the native
     *     part of the library.
     */
    public void flush(final FlushOptions flushOptions,
                      final ColumnFamilyHandle columnFamilyHandle) throws RocksDBException {
        flush(nativeHandle_, flushOptions.nativeHandle_,
                columnFamilyHandle.nativeHandle_);
    }

    /**
     * <p>Range compaction of database.</p>
     * <p><strong>Note</strong>: After the database has been compacted,
     * all data will have been pushed down to the last level containing
     * any data.</p>
     *
     * <p><strong>See also</strong></p>
     * <ul>
     * <li>{@link #compactRange(boolean, int, int)}</li>
     * <li>{@link #compactRange(byte[], byte[])}</li>
     * <li>{@link #compactRange(byte[], byte[], boolean, int, int)}</li>
     * </ul>
     *
     * @throws RocksDBException thrown if an error occurs within the native
     *     part of the library.
     */
    public void compactRange() throws RocksDBException {
        compactRange0(nativeHandle_, false, -1, 0);
    }

    /**
     * <p>Range compaction of database.</p>
     * <p><strong>Note</strong>: After the database has been compacted,
     * all data will have been pushed down to the last level containing
     * any data.</p>
     *
     * <p><strong>See also</strong></p>
     * <ul>
     * <li>{@link #compactRange()}</li>
     * <li>{@link #compactRange(boolean, int, int)}</li>
     * <li>{@link #compactRange(byte[], byte[], boolean, int, int)}</li>
     * </ul>
     *
     * @param begin start of key range (included in range)
     * @param end end of key range (excluded from range)
     *
     * @throws RocksDBException thrown if an error occurs within the native
     *     part of the library.
     */
    public void compactRange(final byte[] begin, final byte[] end)
            throws RocksDBException {
        compactRange0(nativeHandle_, begin, begin.length, end,
                end.length, false, -1, 0);
    }

    /**
     * <p>Range compaction of database.</p>
     * <p><strong>Note</strong>: After the database has been compacted,
     * all data will have been pushed down to the last level containing
     * any data.</p>
     *
     * <p>Compaction outputs should be placed in options.db_paths
     * [target_path_id]. Behavior is undefined if target_path_id is
     * out of range.</p>
     *
     * <p><strong>See also</strong></p>
     * <ul>
     * <li>{@link #compactRange()}</li>
     * <li>{@link #compactRange(byte[], byte[])}</li>
     * <li>{@link #compactRange(byte[], byte[], boolean, int, int)}</li>
     * </ul>
     *
     * @deprecated Use {@link #compactRange(ColumnFamilyHandle, byte[], byte[], CompactRangeOptions)} instead
     *
     * @param reduce_level reduce level after compaction
     * @param target_level target level to compact to
     * @param target_path_id the target path id of output path
     *
     * @throws RocksDBException thrown if an error occurs within the native
     *     part of the library.
     */
    @Deprecated
    public void compactRange(final boolean reduce_level,
                             final int target_level, final int target_path_id)
            throws RocksDBException {
        compactRange0(nativeHandle_, reduce_level,
                target_level, target_path_id);
    }


    /**
     * <p>Range compaction of database.</p>
     * <p><strong>Note</strong>: After the database has been compacted,
     * all data will have been pushed down to the last level containing
     * any data.</p>
     *
     * <p>Compaction outputs should be placed in options.db_paths
     * [target_path_id]. Behavior is undefined if target_path_id is
     * out of range.</p>
     *
     * <p><strong>See also</strong></p>
     * <ul>
     * <li>{@link #compactRange()}</li>
     * <li>{@link #compactRange(boolean, int, int)}</li>
     * <li>{@link #compactRange(byte[], byte[])}</li>
     * </ul>
     *
     * @deprecated Use {@link #compactRange(ColumnFamilyHandle, byte[], byte[], CompactRangeOptions)} instead
     *
     * @param begin start of key range (included in range)
     * @param end end of key range (excluded from range)
     * @param reduce_level reduce level after compaction
     * @param target_level target level to compact to
     * @param target_path_id the target path id of output path
     *
     * @throws RocksDBException thrown if an error occurs within the native
     *     part of the library.
     */
    @Deprecated
    public void compactRange(final byte[] begin, final byte[] end,
                             final boolean reduce_level, final int target_level,
                             final int target_path_id) throws RocksDBException {
        compactRange0(nativeHandle_, begin, begin.length, end, end.length,
                reduce_level, target_level, target_path_id);
    }

    /**
     * <p>Range compaction of column family.</p>
     * <p><strong>Note</strong>: After the database has been compacted,
     * all data will have been pushed down to the last level containing
     * any data.</p>
     *
     * <p><strong>See also</strong></p>
     * <ul>
     * <li>
     *   {@link #compactRange(ColumnFamilyHandle, boolean, int, int)}
     * </li>
     * <li>
     *   {@link #compactRange(ColumnFamilyHandle, byte[], byte[])}
     * </li>
     * <li>
     *   {@link #compactRange(ColumnFamilyHandle, byte[], byte[],
     *   boolean, int, int)}
     * </li>
     * </ul>
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance.
     *
     * @throws RocksDBException thrown if an error occurs within the native
     *     part of the library.
     */
    public void compactRange(final ColumnFamilyHandle columnFamilyHandle)
            throws RocksDBException {
        compactRange(nativeHandle_, false, -1, 0,
                columnFamilyHandle.nativeHandle_);
    }

    /**
     * <p>Range compaction of column family.</p>
     * <p><strong>Note</strong>: After the database has been compacted,
     * all data will have been pushed down to the last level containing
     * any data.</p>
     *
     * <p><strong>See also</strong></p>
     * <ul>
     * <li>{@link #compactRange(ColumnFamilyHandle)}</li>
     * <li>
     *   {@link #compactRange(ColumnFamilyHandle, boolean, int, int)}
     * </li>
     * <li>
     *   {@link #compactRange(ColumnFamilyHandle, byte[], byte[],
     *   boolean, int, int)}
     * </li>
     * </ul>
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance.
     * @param begin start of key range (included in range)
     * @param end end of key range (excluded from range)
     *
     * @throws RocksDBException thrown if an error occurs within the native
     *     part of the library.
     */
    public void compactRange(final ColumnFamilyHandle columnFamilyHandle,
                             final byte[] begin, final byte[] end) throws RocksDBException {
        compactRange(nativeHandle_, begin, begin.length, end, end.length,
                false, -1, 0, columnFamilyHandle.nativeHandle_);
    }


    /**
     * <p>Range compaction of column family.</p>
     * <p><strong>Note</strong>: After the database has been compacted,
     * all data will have been pushed down to the last level containing
     * any data.</p>
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle} instance.
     * @param begin start of key range (included in range)
     * @param end end of key range (excluded from range)
     * @param compactRangeOptions options for the compaction
     *
     * @throws RocksDBException thrown if an error occurs within the native
     *     part of the library.
     */
    public void compactRange(final ColumnFamilyHandle columnFamilyHandle,
                             final byte[] begin, final byte[] end, CompactRangeOptions compactRangeOptions) throws RocksDBException {
        compactRange(nativeHandle_, begin, begin.length, end, end.length,
                compactRangeOptions.nativeHandle_, columnFamilyHandle.nativeHandle_);
    }

    /**
     * <p>Range compaction of column family.</p>
     * <p><strong>Note</strong>: After the database has been compacted,
     * all data will have been pushed down to the last level containing
     * any data.</p>
     *
     * <p>Compaction outputs should be placed in options.db_paths
     * [target_path_id]. Behavior is undefined if target_path_id is
     * out of range.</p>
     *
     * <p><strong>See also</strong></p>
     * <ul>
     * <li>{@link #compactRange(ColumnFamilyHandle)}</li>
     * <li>
     *   {@link #compactRange(ColumnFamilyHandle, byte[], byte[])}
     * </li>
     * <li>
     *   {@link #compactRange(ColumnFamilyHandle, byte[], byte[],
     *   boolean, int, int)}
     * </li>
     * </ul>
     *
     * @deprecated Use {@link #compactRange(ColumnFamilyHandle, byte[], byte[], CompactRangeOptions)} instead
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance.
     * @param reduce_level reduce level after compaction
     * @param target_level target level to compact to
     * @param target_path_id the target path id of output path
     *
     * @throws RocksDBException thrown if an error occurs within the native
     *     part of the library.
     */
    @Deprecated
    public void compactRange(final ColumnFamilyHandle columnFamilyHandle,
                             final boolean reduce_level, final int target_level,
                             final int target_path_id) throws RocksDBException {
        compactRange(nativeHandle_, reduce_level, target_level,
                target_path_id, columnFamilyHandle.nativeHandle_);
    }

    /**
     * <p>Range compaction of column family.</p>
     * <p><strong>Note</strong>: After the database has been compacted,
     * all data will have been pushed down to the last level containing
     * any data.</p>
     *
     * <p>Compaction outputs should be placed in options.db_paths
     * [target_path_id]. Behavior is undefined if target_path_id is
     * out of range.</p>
     *
     * <p><strong>See also</strong></p>
     * <ul>
     * <li>{@link #compactRange(ColumnFamilyHandle)}</li>
     * <li>
     *   {@link #compactRange(ColumnFamilyHandle, boolean, int, int)}
     * </li>
     * <li>
     *   {@link #compactRange(ColumnFamilyHandle, byte[], byte[])}
     * </li>
     * </ul>
     *
     * @deprecated Use {@link #compactRange(ColumnFamilyHandle, byte[], byte[], CompactRangeOptions)} instead
     *
     * @param columnFamilyHandle {@link org.rocksdb.ColumnFamilyHandle}
     *     instance.
     * @param begin start of key range (included in range)
     * @param end end of key range (excluded from range)
     * @param reduce_level reduce level after compaction
     * @param target_level target level to compact to
     * @param target_path_id the target path id of output path
     *
     * @throws RocksDBException thrown if an error occurs within the native
     *     part of the library.
     */
    @Deprecated
    public void compactRange(final ColumnFamilyHandle columnFamilyHandle,
                             final byte[] begin, final byte[] end, final boolean reduce_level,
                             final int target_level, final int target_path_id)
            throws RocksDBException {
        compactRange(nativeHandle_, begin, begin.length, end, end.length,
                reduce_level, target_level, target_path_id,
                columnFamilyHandle.nativeHandle_);
    }

    /**
     * This function will wait until all currently running background processes
     * finish. After it returns, no background process will be run until
     * {@link #continueBackgroundWork()} is called
     *
     * @throws RocksDBException If an error occurs when pausing background work
     */
    public void pauseBackgroundWork() throws RocksDBException {
        pauseBackgroundWork(nativeHandle_);
    }

    /**
     * Resumes backround work which was suspended by
     * previously calling {@link #pauseBackgroundWork()}
     *
     * @throws RocksDBException If an error occurs when resuming background work
     */
    public void continueBackgroundWork() throws RocksDBException {
        continueBackgroundWork(nativeHandle_);
    }

    /**
     * <p>The sequence number of the most recent transaction.</p>
     *
     * @return sequence number of the most
     *     recent transaction.
     */
    public long getLatestSequenceNumber() {
        return getLatestSequenceNumber(nativeHandle_);
    }

    /**
     * <p>Prevent file deletions. Compactions will continue to occur,
     * but no obsolete files will be deleted. Calling this multiple
     * times have the same effect as calling it once.</p>
     *
     * @throws RocksDBException thrown if operation was not performed
     *     successfully.
     */
    public void disableFileDeletions() throws RocksDBException {
        disableFileDeletions(nativeHandle_);
    }

    /**
     * <p>Allow compactions to delete obsolete files.
     * If force == true, the call to EnableFileDeletions()
     * will guarantee that file deletions are enabled after
     * the call, even if DisableFileDeletions() was called
     * multiple times before.</p>
     *
     * <p>If force == false, EnableFileDeletions will only
     * enable file deletion after it's been called at least
     * as many times as DisableFileDeletions(), enabling
     * the two methods to be called by two threads
     * concurrently without synchronization
     * -- i.e., file deletions will be enabled only after both
     * threads call EnableFileDeletions()</p>
     *
     * @param force boolean value described above.
     *
     * @throws RocksDBException thrown if operation was not performed
     *     successfully.
     */
    public void enableFileDeletions(final boolean force)
            throws RocksDBException {
        enableFileDeletions(nativeHandle_, force);
    }

    /**
     * <p>Returns an iterator that is positioned at a write-batch containing
     * seq_number. If the sequence number is non existent, it returns an iterator
     * at the first available seq_no after the requested seq_no.</p>
     *
     * <p>Must set WAL_ttl_seconds or WAL_size_limit_MB to large values to
     * use this api, else the WAL files will get
     * cleared aggressively and the iterator might keep getting invalid before
     * an update is read.</p>
     *
     * @param sequenceNumber sequence number offset
     *
     * @return {@link org.rocksdb.TransactionLogIterator} instance.
     *
     * @throws org.rocksdb.RocksDBException if iterator cannot be retrieved
     *     from native-side.
     */
    public TransactionLogIterator getUpdatesSince(final long sequenceNumber)
            throws RocksDBException {
        return new TransactionLogIterator(
                getUpdatesSince(nativeHandle_, sequenceNumber));
    }

    public void setOptions(final ColumnFamilyHandle columnFamilyHandle,
                           final MutableColumnFamilyOptions mutableColumnFamilyOptions)
            throws RocksDBException {
        setOptions(nativeHandle_, columnFamilyHandle.nativeHandle_,
                mutableColumnFamilyOptions.getKeys(),
                mutableColumnFamilyOptions.getValues());
    }

    private long[] toNativeHandleList(final List<? extends RocksObject> objectList) {
        final int len = objectList.size();
        final long[] handleList = new long[len];
        for (int i = 0; i < len; i++) {
            handleList[i] = objectList.get(i).nativeHandle_;
        }
        return handleList;
    }

    /**
     * ingestExternalFile will load a list of external SST files (1) into the DB
     * We will try to find the lowest possible level that the file can fit in, and
     * ingest the file into this level (2). A file that have a key range that
     * overlap with the memtable key range will require us to Flush the memtable
     * first before ingesting the file.
     *
     * (1) External SST files can be created using {@link SstFileWriter}
     * (2) We will try to ingest the files to the lowest possible level
     * even if the file compression doesn't match the level compression
     *
     * @param filePathList The list of files to ingest
     * @param ingestExternalFileOptions the options for the ingestion
     *
     * @throws RocksDBException thrown if error happens in underlying
     *     native library.
     */
    public void ingestExternalFile(final List<String> filePathList,
                                   final IngestExternalFileOptions ingestExternalFileOptions)
            throws RocksDBException {
        ingestExternalFile(nativeHandle_, getDefaultColumnFamily().nativeHandle_,
                filePathList.toArray(new String[filePathList.size()]),
                filePathList.size(), ingestExternalFileOptions.nativeHandle_);
    }

    /**
     * ingestExternalFile will load a list of external SST files (1) into the DB
     * We will try to find the lowest possible level that the file can fit in, and
     * ingest the file into this level (2). A file that have a key range that
     * overlap with the memtable key range will require us to Flush the memtable
     * first before ingesting the file.
     *
     * (1) External SST files can be created using {@link SstFileWriter}
     * (2) We will try to ingest the files to the lowest possible level
     * even if the file compression doesn't match the level compression
     *
     * @param columnFamilyHandle The column family for the ingested files
     * @param filePathList The list of files to ingest
     * @param ingestExternalFileOptions the options for the ingestion
     *
     * @throws RocksDBException thrown if error happens in underlying
     *     native library.
     */
    public void ingestExternalFile(final ColumnFamilyHandle columnFamilyHandle,
                                   final List<String> filePathList,
                                   final IngestExternalFileOptions ingestExternalFileOptions)
            throws RocksDBException {
        ingestExternalFile(nativeHandle_, columnFamilyHandle.nativeHandle_,
                filePathList.toArray(new String[filePathList.size()]),
                filePathList.size(), ingestExternalFileOptions.nativeHandle_);
    }

    /**
     * Static method to destroy the contents of the specified database.
     * Be very careful using this method.
     *
     * @param path the path to the Rocksdb database.
     * @param options {@link org.rocksdb.Options} instance.
     *
     * @throws RocksDBException thrown if error happens in underlying
     *    native library.
     */
    public static void destroyDB(final String path, final Options options)
            throws RocksDBException {
        destroyDB(path, options.nativeHandle_);
    }

    /**
     * Private constructor.
     *
     * @param nativeHandle The native handle of the C++ RocksDB object
     */
    protected RocksDB(final long nativeHandle) {
        super(nativeHandle);
    }

    // native methods
    protected native static long open(final long optionsHandle,
                                      final String path) throws RocksDBException;

    /**
     * @param optionsHandle Native handle pointing to an Options object
     * @param path The directory path for the database files
     * @param columnFamilyNames An array of column family names
     * @param columnFamilyOptions An array of native handles pointing to
     *                            ColumnFamilyOptions objects
     *
     * @return An array of native handles, [0] is the handle of the RocksDB object
     *   [1..1+n] are handles of the ColumnFamilyReferences
     *
     * @throws RocksDBException thrown if the database could not be opened
     */
    protected native static long[] open(final long optionsHandle,
                                        final String path, final byte[][] columnFamilyNames,
                                        final long[] columnFamilyOptions) throws RocksDBException;

    protected native static long openROnly(final long optionsHandle,
                                           final String path) throws RocksDBException;

    /**
     * @param optionsHandle Native handle pointing to an Options object
     * @param path The directory path for the database files
     * @param columnFamilyNames An array of column family names
     * @param columnFamilyOptions An array of native handles pointing to
     *                            ColumnFamilyOptions objects
     *
     * @return An array of native handles, [0] is the handle of the RocksDB object
     *   [1..1+n] are handles of the ColumnFamilyReferences
     *
     * @throws RocksDBException thrown if the database could not be opened
     */
    protected native static long[] openROnly(final long optionsHandle,
                                             final String path, final byte[][] columnFamilyNames,
                                             final long[] columnFamilyOptions
    ) throws RocksDBException;

    protected native static byte[][] listColumnFamilies(long optionsHandle,
                                                        String path) throws RocksDBException;
    protected native void put(long handle, byte[] key, int keyOffset,
                              int keyLength, byte[] value, int valueOffset, int valueLength)
            throws RocksDBException;
    protected native void put(long handle, byte[] key, int keyOffset,
                              int keyLength, byte[] value, int valueOffset, int valueLength,
                              long cfHandle) throws RocksDBException;
    protected native void put(long handle, long writeOptHandle, byte[] key,
                              int keyOffset, int keyLength, byte[] value, int valueOffset,
                              int valueLength) throws RocksDBException;
    protected native void put(long handle, long writeOptHandle, byte[] key,
                              int keyOffset, int keyLength, byte[] value, int valueOffset,
                              int valueLength, long cfHandle) throws RocksDBException;
    protected native void write0(final long handle, long writeOptHandle,
                                 long wbHandle) throws RocksDBException;
    protected native void write1(final long handle, long writeOptHandle,
                                 long wbwiHandle) throws RocksDBException;
    protected native boolean keyMayExist(final long handle, final byte[] key,
                                         final int keyOffset, final int keyLength,
                                         final StringBuilder stringBuilder);
    protected native boolean keyMayExist(final long handle, final byte[] key,
                                         final int keyOffset, final int keyLength, final long cfHandle,
                                         final StringBuilder stringBuilder);
    protected native boolean keyMayExist(final long handle,
                                         final long optionsHandle, final byte[] key, final int keyOffset,
                                         final int keyLength, final StringBuilder stringBuilder);
    protected native boolean keyMayExist(final long handle,
                                         final long optionsHandle, final byte[] key, final int keyOffset,
                                         final int keyLength, final long cfHandle,
                                         final StringBuilder stringBuilder);
    protected native void merge(long handle, byte[] key, int keyOffset,
                                int keyLength, byte[] value, int valueOffset, int valueLength)
            throws RocksDBException;
    protected native void merge(long handle, byte[] key, int keyOffset,
                                int keyLength, byte[] value, int valueOffset, int valueLength,
                                long cfHandle) throws RocksDBException;
    protected native void merge(long handle, long writeOptHandle, byte[] key,
                                int keyOffset, int keyLength, byte[] value, int valueOffset,
                                int valueLength) throws RocksDBException;
    protected native void merge(long handle, long writeOptHandle, byte[] key,
                                int keyOffset, int keyLength, byte[] value, int valueOffset,
                                int valueLength, long cfHandle) throws RocksDBException;
    protected native int get(long handle, byte[] key, int keyOffset,
                             int keyLength, byte[] value, int valueOffset, int valueLength)
            throws RocksDBException;
    protected native int get(long handle, byte[] key, int keyOffset,
                             int keyLength, byte[] value, int valueOffset, int valueLength,
                             long cfHandle) throws RocksDBException;
    protected native int get(long handle, long readOptHandle, byte[] key,
                             int keyOffset, int keyLength, byte[] value, int valueOffset,
                             int valueLength) throws RocksDBException;
    protected native int get(long handle, long readOptHandle, byte[] key,
                             int keyOffset, int keyLength, byte[] value, int valueOffset,
                             int valueLength, long cfHandle) throws RocksDBException;
    protected native byte[][] multiGet(final long dbHandle, final byte[][] keys,
                                       final int[] keyOffsets, final int[] keyLengths);
    protected native byte[][] multiGet(final long dbHandle, final byte[][] keys,
                                       final int[] keyOffsets, final int[] keyLengths,
                                       final long[] columnFamilyHandles);
    protected native byte[][] multiGet(final long dbHandle, final long rOptHandle,
                                       final byte[][] keys, final int[] keyOffsets, final int[] keyLengths);
    protected native byte[][] multiGet(final long dbHandle, final long rOptHandle,
                                       final byte[][] keys, final int[] keyOffsets, final int[] keyLengths,
                                       final long[] columnFamilyHandles);
    protected native byte[] get(long handle, byte[] key, int keyOffset,
                                int keyLength) throws RocksDBException;
    protected native byte[] get(long handle, byte[] key, int keyOffset,
                                int keyLength, long cfHandle) throws RocksDBException;
    protected native byte[] get(long handle, long readOptHandle,
                                byte[] key, int keyOffset, int keyLength) throws RocksDBException;
    protected native byte[] get(long handle, long readOptHandle, byte[] key,
                                int keyOffset, int keyLength, long cfHandle) throws RocksDBException;
    protected native void delete(long handle, byte[] key, int keyOffset,
                                 int keyLength) throws RocksDBException;
    protected native void delete(long handle, byte[] key, int keyOffset,
                                 int keyLength, long cfHandle) throws RocksDBException;
    protected native void delete(long handle, long writeOptHandle, byte[] key,
                                 int keyOffset, int keyLength) throws RocksDBException;
    protected native void delete(long handle, long writeOptHandle, byte[] key,
                                 int keyOffset, int keyLength, long cfHandle) throws RocksDBException;
    protected native void singleDelete(
            long handle, byte[] key, int keyLen) throws RocksDBException;
    protected native void singleDelete(
            long handle, byte[] key, int keyLen, long cfHandle)
            throws RocksDBException;
    protected native void singleDelete(
            long handle, long writeOptHandle,
            byte[] key, int keyLen) throws RocksDBException;
    protected native void singleDelete(
            long handle, long writeOptHandle,
            byte[] key, int keyLen, long cfHandle) throws RocksDBException;
    protected native void deleteRange(long handle, byte[] beginKey, int beginKeyOffset,
                                      int beginKeyLength, byte[] endKey, int endKeyOffset, int endKeyLength)
            throws RocksDBException;
    protected native void deleteRange(long handle, byte[] beginKey, int beginKeyOffset,
                                      int beginKeyLength, byte[] endKey, int endKeyOffset, int endKeyLength, long cfHandle)
            throws RocksDBException;
    protected native void deleteRange(long handle, long writeOptHandle, byte[] beginKey,
                                      int beginKeyOffset, int beginKeyLength, byte[] endKey, int endKeyOffset, int endKeyLength)
            throws RocksDBException;
    protected native void deleteRange(long handle, long writeOptHandle, byte[] beginKey,
                                      int beginKeyOffset, int beginKeyLength, byte[] endKey, int endKeyOffset, int endKeyLength,
                                      long cfHandle) throws RocksDBException;
    protected native String getProperty0(long nativeHandle,
                                         String property, int propertyLength) throws RocksDBException;
    protected native String getProperty0(long nativeHandle, long cfHandle,
                                         String property, int propertyLength) throws RocksDBException;
    protected native long getLongProperty(long nativeHandle, String property,
                                          int propertyLength) throws RocksDBException;
    protected native long getLongProperty(long nativeHandle, long cfHandle,
                                          String property, int propertyLength) throws RocksDBException;
    protected native long getAggregatedLongProperty(long nativeHandle, String property,
                                                    int propertyLength) throws RocksDBException;
    protected native long iterator(long handle);
    protected native long iterator(long handle, long readOptHandle);
    protected native long iteratorCF(long handle, long cfHandle);
    protected native long iteratorCF(long handle, long cfHandle,
                                     long readOptHandle);
    protected native long[] iterators(final long handle,
                                      final long[] columnFamilyHandles, final long readOptHandle)
            throws RocksDBException;
    protected native long getSnapshot(long nativeHandle);
    protected native void releaseSnapshot(
            long nativeHandle, long snapshotHandle);
    @Override protected native void disposeInternal(final long handle);
    private native long getDefaultColumnFamily(long handle);
    private native long createColumnFamily(final long handle,
                                           final byte[] columnFamilyName, final long columnFamilyOptions)
            throws RocksDBException;
    private native void dropColumnFamily(long handle, long cfHandle)
            throws RocksDBException;
    private native void flush(long handle, long flushOptHandle)
            throws RocksDBException;
    private native void flush(long handle, long flushOptHandle, long cfHandle)
            throws RocksDBException;
    private native void compactRange0(long handle, boolean reduce_level,
                                      int target_level, int target_path_id) throws RocksDBException;
    private native void compactRange0(long handle, byte[] begin, int beginLen,
                                      byte[] end, int endLen, boolean reduce_level, int target_level,
                                      int target_path_id) throws RocksDBException;
    private native void compactRange(long handle, byte[] begin, int beginLen,
                                     byte[] end, int endLen, long compactRangeOptHandle, long cfHandle)
            throws RocksDBException;
    private native void compactRange(long handle, boolean reduce_level,
                                     int target_level, int target_path_id, long cfHandle)
            throws RocksDBException;
    private native void compactRange(long handle, byte[] begin, int beginLen,
                                     byte[] end, int endLen, boolean reduce_level, int target_level,
                                     int target_path_id, long cfHandle) throws RocksDBException;
    private native void pauseBackgroundWork(long handle) throws RocksDBException;
    private native void continueBackgroundWork(long handle) throws RocksDBException;
    private native long getLatestSequenceNumber(long handle);
    private native void disableFileDeletions(long handle) throws RocksDBException;
    private native void enableFileDeletions(long handle, boolean force)
            throws RocksDBException;
    private native long getUpdatesSince(long handle, long sequenceNumber)
            throws RocksDBException;
    private native void setOptions(long handle, long cfHandle, String[] keys,
                                   String[] values) throws RocksDBException;
    private native void ingestExternalFile(long handle, long cfHandle,
                                           String[] filePathList, int filePathListLen,
                                           long ingest_external_file_options_handle) throws RocksDBException;
    private native static void destroyDB(final String path,
                                         final long optionsHandle) throws RocksDBException;
    protected DBOptionsInterface options_;
}
